Motor control.



E. R. CARICHOFF. MOTOR CONTROL.

APPLICATION FILED OCT. 24. I9I6 Patented Dc. 10, 1918 Irfiventor': Eugene IQ.Car-ichof'f-,

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at Schenectady,- county of =Schenectady, 5 State of New York, have invented certain new -and useful Improvements in Motor invention relates to the control-of an electric motor and it provides improved @hiitrols, of whiclr'the following is zit-specifiiiieansfwhereby the motor maybe started,

p'd', and generally controlled in a simreliable and efficient manner.

y invention has a particularusefulness '15"i n'the starting of larger sizesof electric meters; Such'motors are ordinarily started by ncluding a resista'nce' 1n the motor circuit and electromagnetically jactuated switches having shunt coils 'are'prox'i ded-for cutting out sections'of this res'istanceas the speed of. the motor increases and the motor current drops. Series current limit relays responsive to the mainniotor -current have "heretofore been PIOVldEClfOl energizing the windings of these switches-to'cut outthe resistance at the proper time and interlocks were provided for securingthe desired sequence of operation of the switches. These interlocks have been objectionable because f80" of the difficulty ofsecuring good-electrical contact due to dust collecting on the interlocks, corrosion and the pitting caused by the arcs formed as'thefcircnits at the interlocks are broken. One of theobje'ct-s of my '35"invention is to retain the electromagnetic ally actuated switches having shunt- 'wind- -'ings and eliminate the troublesome inter- '-locks. In carrying'my invention intoefi'ect, flfprovide' a "plurality of series contactors, 40f onefor theiwindingcircuit of each switch,

and use these contactors as current limitreil'giy's. These seriescontactors may be'of-the :"Melll known typewhich are held oped-when y "tlfe o'perating' currc'nt' is high and-*ar' '14s xiflin the operating current rails-r0; iitefiitined value. Thesecoiitactors 11" f net' d' so that they will' operate? succesf isfidiif'fresponsivelyi tothe motor current", the sista-nce in the mot orc1rcu1t-. 7 Each of the rr'lhgement beingfsnch that each 'contactor lilrrcrnvri It; Ganrcrr- 1 OFF, a cltizen of the United"States,"residing n w-gummy,

i in closing short circuits a resistance in 'the winding'of an electromagnetically actuated resistance switchthereby causing this "switch to operate andcutout asection of resistance in the motor circuit. The closing of the resistance switch short circuits the series contactor whi'clraused it-to open and "re-inserts the resistance in the winding circuit of the resistance switch.

is also simultaneously included in'the motor circuit. By this arrangement the defects of theordinary series current limit relays are avoided as the contacts can all be closed by a; positive'magne'ticforce and given a wiping action to insure good electrical contact. Furthcrmore,.the series contactors, which in my arrangement'are used as relays, 'can'all be made relatively quite small as they are The coil of the next series contactor of the succession required to carry-the full motor current for aver short period}! Referring to; the drawin the single figure of which shows diagrammaticallythe 1 control for an electric motor embodying my invention, the electric motor M having an armature and series field has includedin its armature circuit at starting the sections of resistance R, R R "These sections of resistanceare short circuited-by i'neans of the electromagnetic resistance switches having contact membersh- 2 -an'd=3.- The magnet windings l, 5 and 6 of these switches are energized in a shunt or independent circuit to themotor circuit and' are controlled-by means of series contact-ors 7,-8 and 9:- re'-' spectively; These seriesjcontactorsuact as current limit're'lay's to control the 'operation of-the electromagnetic resistance switches, and as shown, they-areof the well known type which holdopen whenthecurrent is -,high and close when thecurrent -drops to a predetermined value: These series contacg'tots areconnected i'n'the' armature circuitin succession L andi-cachfl'contactor closing short l circuits a resi'stance 'inft-he winding "cir cuit of "its respective electromagnetic 'rc- -c sistance switcht causing the'resi'stance switch toclose and'short circuit a section of reelectromagnetic resistance switches in clos- 4 ing not only short circuits a section of the armature resistance, but also short circuits the wind-mg of the series contactor which -'caused'it to operate .and at the same time includes the winding ofthe next series con- .tactor in the success oninthe motor circuit.

The contact member of each of'the series contactors is electrically connected .to its coil circuit and to the winding ,circuit of its respective electromagnetic resistance I switch. By closing a pilot switch 10 in the coil circuit'ofthe electromagnetically actuated lineswitch 11, this line switch is ener- .gized to close the motor-- armature circuit,

The electromagnetically actuated-switch 11' has, an interlock which completes the circuit for the windings 4, 5 and 6 of the electromagnetic resistanceswitches;

In order to start the motorthe pilot switch 10 is first closed." This energizes the coil of the. electromagnetically actuated switch 11, causing this switch to pickup its" contact member and close the motor circuit,

at the same time completing the circuit for the windings, 4, ,5 and 6 at theinterlock 12,

' p the circuit-for. these windings being through tromagnetically actuated switch 11, coil ofthe coils of series-conta'ctors 7, 8 and 9 and the resistances 13, 14 and 15, respectively.

The resistances 13, 14.- and 15 are of such value that suflicient current will not flow [through the .windings to close the switches.

The motor circuitis now from the sourceofsupply through'the contact member of elecseries contactor 7, starting resistances R R B, through the armature and series field of the motor to ground. The contact member of series oQntactor'Z will be magnetically.

held open when the inotor'current is above the-predetermined value due to the increased 1 a predetermined value and will be magnetically closed and held closed when the motor current drops below that predctermine value.

When the contact of series contactor 7 closes after the motor-current has dropped below speed of the motor,- it closes a short circuit around the resistance 13 and energizes the first electromagnetic -resistance,switch to close and cause-contact member i to out out the first section R of the starting resistance,

the circuit for the winding 2 being through ,-netic resistance switch closes it not only cuts out the first section B oif-- the starting resistance but at the same. time short circuits the coil of series contactor. 7 which cau'sedit to operate, the short circuit' including the;

series coil of series contactor 8; The coil of The operation of my device is as follows motor circuit. Short circuiting the coil of series con-tactor 7 causes this contactorto open and re-insert the rcs1stance-13 in the circuit of the winding 4. The electromag--- netic resistance switchw'ill not open since this resistance will permit suflicient .cuirent to How through the winding 4 to maintain the contact "member 1 closed. After the motor current drops to the predetermined value due to the-increased speed. of the motor armaturef the series' contactor Y 8 will close and short circuit the resistance 1 1, permitting the winding 5 to close the switch member 2, cutting out the second section ofstartzing resistance R causing the series contactor 8 to open the short circuit around resistance 14, and at the same time including the coil of series contactor '9 in the 'motor circuit. The principle of'operation of-the series con-' tactor 9' is the same as series contactor's 7 and 8; namely, in closing it causes the winding 6 to be energized picking up the contact member 3, short circuiting the lastsectionlRs of the starting resistance and opening the series c'ontactor 9, re-insert'ing the. resistance 15 in the circuit of winding 6. In order to stop themotor the pilot switch 10 is opened thus. opening the, electromagnetic switch 11 and the electromagnetic resistance switches.

It will readily be seen that my arrangement makes possible the use of electromagnetic switches having their windings energiz ed through circults independent of the motor armature circuit, and that none of the troublesome interlockshave been necessary to secure the desired progression of these electromagnetic resistance switches. The series contactors 7, 8 and 9 can be made relatively quite small becauseof the fact that they are required to carry the full armature current fora very short period in starting. The contactors have the great advantage that their contactmembers make positive-electrical contact. In the typeof series contactor whichI have chosen for purposes of illustration, the. contact members are closed and held closed by magnetic force and given a wiping action'as they close, thus insuring positive. electrical contacts and positive operation of the electromagnetic switches. j

' In accordance with the prpvisions'ofthe patent statutes, '1 have described the principle of operation of my invention, together I with the apparatus which I now consider to represent the best embodiment thereof; but Idesire. to have it understood tliatthe apparatus shown is only illustrative, and that the invention canbecarried out by othermeans.

What-I claim as new and desire to secure by Letters Patent of the United States, is 1 I. The combination with an electric motor of means for starting the same, comprising eaner? a plurality of electromagnetic switches for ently of the motor armature circuit, a plurality of electromagnetic switches energized by current in the armature circuit and arranged to hold open when the current in the armature circuit is high and close when the current falls to a predetermined value, each of said latter switches in closing causing one of the resistance switches to operate, and connections whereby each resistance switch in closing causes the opening of the electromagnetic switch which caused it to operate.

2. The combination with an electric motor of means for starting the same, comprising a plurality of electromagnetic switches for cutting out resistance from the motor circuit, a plurality of series contactors energized by current in the armature circuit and arranged to hold open when the currentin the armature circuit is high and'close when the current falls to a predetermined value, each of said series contactors in closing causing one of the resistance switches to operate and open the series oontactor which caused the resistance switch to operate.

3. The combination with an electricmotor of means for starting the same, comprising a plurality of electromagnetic switches for cutting out resistance from the motor circuit, a plurality of series contactors energized. in succession by currentin the armature circuit and arranged to hold open when the current in the armature circuit is high and close'when the current falls to a predetermined value, each of said series contactors in closing causing one of the resistance switches to operate, and connections whereby each resistance switch in closing opens the series cont-actor which caused it to operate and energizes the next series contactor in the succession.

at. The combination with an electric motor of means for starting the same, comprising a plurality of electromagnetic switches for cutting out resistance from the motor circuit, a plurality of normally opened series contactors. energized in succession by current in the armature circuit and arranged to hold open when the current in the arma-' ture circuit is high and close when the current falls to a predetermined value, each of said series contactors in closing causing one of the resistance switches to operate, and connections whereby each resistance switch in closing short circuits the winding of the series contactor which caused it to operate and includes the winding of the next series contactor in succession in the motor armature circuit. I

The combination with an electric motor of means for starting the same, comprising an electromagnetic switch for cutting out resistance from the motor circuit, a winding for said switch energized independently of the motor circuit, a resistance in the circuit of said winding. :1 series contactor energized by current in the motor circuit having its coil connected to its contact member and to the winding of the electromagnetic switch. the said contactor arranged to hold open when the current is high and to short circuitthe resistance in the winding circuit of the electromagnetic switch when the current falls to a predetermined value, causing the electromagnetic switch to operate and cut out resistance from the motor circuit, and connections whereby the electromagnetic switch in closing causes the series contactor to open, re-inserting the resistance in the winding of the elcctrmnagnetic switch.

6. The combination with an electric motor of means for starting the same. comprising a plurality of electromagnetic switches for cutting out resistance from the motor circuit. each having a winding connected in shunt to the motor through a resistance, a plurality of series contactors energized by current in the armature circuit and arranged to hold open when the current is high and close when the current falls to a predetermined value, each of said series contactors in closing short circuiting a resistance in the winding circuit of one of said switches to cause the switch to operate. and connections whereby the operation of the su itch causes the series contactor to open and reinsert'the resistance in the winding circuit of the resistance switch.

7. The combination with an electric motor of means for starting the same, comprising a plurality of electromagnetic switches for cutting out resistance from the motor circuit, each having a winding connected in shunt to the motor through a resistance. a plurality of series contactors energized in succession bycurrcnt in the armature circuit and arranged to hold open when the current is high and close when the current falls to a predetermined value, each of said series contactors in closing short circuiting a resistance in the winding circuit of one of said switches causing the switch to operate, and connections whereby each resistance switch in closing causes the resistance to be reinserted in its winding circuitand includes the winding of the next series contactor in the succession in the motor armature circuit. Y

S. The combination with an electric motor of meansfor starting thesanic. comprising a plurality of electromagnetic switches for cutting out resistance from the motor circuit, each having a winding connected in shunt to the motor through a resistance, a plurality ofseries contactors energized in -succession by current in the armature circuit and arranged to hold open when the current is high and close when the current falls to a predetermined value, each of said erate, and connections whereby each resistance switch in closing opens the series contactor which caused it to operate and includes the winding of the next series contactor in the succession in the motor ar1nature circuit.

Inwitness whereofllhave hereunto set my hand this 23rd day of October, 1916. I EUGENE R. CARICHOFF 

